Fill power is defined as the degree of expansion of 30 grams of feathers when subjected to a uniform load. A higher fill power means the down incorporates more air, giving even small amounts superb warmth and high performance. UNIQLO down uses 750 fill power or higher*. The result sits nicely between more casual down and specialist outdoor goods. The density and blend of fill, as well as the fabric, water-repellency, and sewing, all influence insulation.

Lacking a hard quill shaft, down has a shape that holds more air, for increased warmth. Feathers have a quill, giving them better flexibility, at the cost of insulation. Down items at UNIQLO use a ratio of 90% down to 10% feathers.* Adding feathers to the mix helps to ensure proper distribution of the fill. For just the right balance, a ratio of 90/10 gives items exemplary warmth while keeping things easy and light.

Down’s sworn enemies are moisture and compression. It’s important to maintain its puffiness through routine care. After wearing, hang your down so that all sweat and moisture can evaporate. Warming your hands before touching the item can help you see if the down inside is compromised by dampness. In warmer months, avoid vacuum bags and instead hang your items up. All down items can be washed by hand. Don’t forget to hang them out to dry on clear days when the air is breezy.